PORSCHE 911 FLOOR PROBLEM

I have a 2003 Porsche 911 C4S. Last year on 3 separate occasions when I had to floor the car whilst cold (so less than 10 minutes after starting) and then stop to idle quite shortly afterwards (common practice in London) I found the engine began to mis-fire and the engine management light came on. On all 3 occasions I sent the car back to the Porsche garage and they failed to diagnose. The problem seemed to rectify itself after a couple of days and the light would go off and the car runs again as normal. Four days ago it came on again after having to floor it and then stop again at lights however this time the light hasn't gone off, and although if i'm driving continuously there are no problems, if i'm sitting idle in traffic or at lights for more than 30 secs it seems to judder and begin to mis-fire again. Please, please do you have any ideas as to what the problem is as I have completely lost faith in the Porsche dealership?

Hey, I hope I can shed some light on your problem, you are dealing with a high performance vehicle and anytime you push the throttle pedal to floor and release as fast as you pushed it, there will be a considerable amount of fuel not burnt in this action which then gets circulated into the exhaust system, this is inirt gas that ends up saturating the converter, what you could try is warming the car up before driving, that means 5 to 10 minutes not seconds, also not flooring the pedal until vehicle is at running temperature will help your symptom, let me know the outcome.